A modern computer system with a large memory (called “main memory” herein) may use virtual addressing in which a virtual memory address issued by a processor must be converted to a real (physical) address in the main memory to read or write the addressed storage area. A conversion table, often called a page table, holds the virtual-to-real cross reference information. However, the page table is usually stored in the main memory itself such that accessing the page table to effect a virtual-to-real conversion for each memory access would be very time consuming. Associative memories have been used for many years to speed up this process.
Associative memories are small, fast memories, directly available to the processor, which store an updateable selection of entries in the page table. The entries are updated when there is a “miss” (the associative memory does not hold the particular virtual-to-real entry requested by the processor) such that the page table must be consulted directly to obtain the requested virtual-to-real address conversion information. However, this particular entry can be sent to the associative memory as a result of the page table access so that the next request for the same virtual-to-real address conversion can be serviced very quickly.
It is sometimes necessary to clear an entire associative memory by marking all entries “invalid”. Embodiments of the invention serve to perform this function very efficiently.